Technical Field
The present invention relates to a flushing control method for an inkjet printer that can appropriately flush two inkjet heads mounted on a carriage, and to an inkjet printer.
Related Art
The nozzles of an inkjet head used in an inkjet printer can become clogged as a result of an increase in the viscosity of ink left inside the nozzles, resulting in the clogged nozzles being unable to discharge sufficient ink. If printing is attempted using an inkjet head in which some nozzles are clogged, dots may be dropped or ill-formed and print quality drops accordingly. Inkjet printers therefore regularly or at specified times move the carriage that carries the inkjet head to a home position removed from the printing area so that a head cap with an ink sponge used for maintenance is opposite the nozzle surface of the inkjet head, and then discharge a specific amount of ink from each of the nozzles to flush the nozzles.
An inkjet printer that flushes the nozzles is taught, for example, in Japanese Unexamined Patent Appl. Pub. JP-A-H10-146993. The inkjet printer taught in JP-A-H10-146993 counts the time that the maintenance head cap caps the inkjet head while the carriage is stopped in the home position, and flushes the nozzles regularly based on this time.
When the inkjet head has first and second inkjet heads, a carriage on which the first and second inkjet heads are mounted adjacent to each other in the carriage scanning direction, and a carriage drive mechanism that drives the carriage bidirectionally in the carriage scanning direction, two maintenance head caps could conceivably be provided for maintenance of these two inkjet heads. However, because an ink sponge and suction mechanism for suctioning ink from the nozzles are generally disposed in the maintenance head cap, two suction mechanisms are needed if two maintenance head caps are provided, and construction becomes complicated.
A single maintenance head cap could be disposed to a maintenance position that is opposite the first inkjet head when the carriage moves to the home position and the first inkjet head is closer to the printing area than the second inkjet head. When the nozzles are flushed, the carriage could then be moved in the scanning direction so that each inkjet head is sequentially set to the maintenance position and the nozzles are flushed one inkjet head at a time.
However, in order to flush the second inkjet head, which is positioned on the side separated from the printing area when the carriage is set to the maintenance position as described above, the carriage must move from the home position to the printing area side, causing the first inkjet head to protrude into the printing area side. As a result, if the second inkjet head is flushed before printing starts, printing cannot start unless the carriage is returned to the home position after flushing is completed, and the start of printing is thus delayed. In addition, if the second print head is not flushed in order to avoid delaying the start of printing, dropped dots and other problems can result in a loss of print quality.